monitoring maize n status with airborne and ground level

Monitoring maize N status with airborne and ground level sensors

M. QUEMADA, J.L. GABRIEL, P. ZARCO-TEJADA, J. LÓPEZ-HERRERA, E. PÉREZ-MARTÍN, M.

ALONSO-AYUSO

School of Agricultural Engineering, Technical University of Madrid, SpainInstituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Madrid, Spain.

Instituto de Agricultura Sostenible (IAS-CSIC), Córdoba, Spain

Innovative solutions for a sustainable management of N in agriculture AARHUS 26-28 JUNE

Outline

I. Introduction:- Maize N dynamic

- Available N sensors

II. Experimental setup

III. Results:- Fertiliser rate vs. N uptake

- Remote sensor predicting N content

- Scale resolution effect

IV. Conclusions


Maize yield:vs. crop N uptake vs. N applied as fertilizer

y = 0.0497x - 0.349R² = 0.93

3

5

7

9

11

13

15

50 100 150 200 250 300

Yie

ld (M

g d

m/h

a)

Crop N uptake (kg N/ha)

a)

0 40 80 120 160 200

N applied as fertilizer (kg N/ha)

b)

N applied ≤ 160: Yield = 5.12 + 0.045 N appliedN applied > 160: Yield = 12.32R2 = 0.96

I. Maize N dynamic


From: Quemada et al. 2014. Remote Sensing 6, 2940-2962

I. Maize N dynamic


From: Plénet & Lemaire, 2000. Plant and Soil 216, 65-82

I. Available N sensors



Field Station “La Chimenea”

Zone: Tajo river basin

Climatic conditions:•Mediterranean semiarid

•Monoxeric with 4 dry months (June to September)

•Average annual temperatures:

•20.5 ºC maximum

•14 ºC mean

•6.5 ºC minimum

• Average annual rainfall: 350 mm

•ETo 753 mm

Clasification

Silty clay loam texture pH≈8 OM≈2%Polygenic origin soil appropriate for irrigationFriable structure and porous along the profileWithout erosion, compactation, inundation, and with low stone content throughout the profile

Typic calcixerept (Soil Survey Staff, 2003)Haplic calcisol (FAO-UNESCO, 1988) Ocric

Cambic

Calcic


0.0

0.1

0.2

0.3

0.4

0.5

400 500 600 700 800

Re

fle

cta

nce

Wavelength (nm)

Stressed

Healthy





Index DefinitionSPAD

SPAD Ratio of transmitted light at the red and infrared wavelengths

Dualex® ScientificChl Ratio of transmitted light at two infrared wavelengths

Flav Log of the fluerescence emission ratio at the red and UV wavelengths

NBI Nitrogen Balance Index = Chl / FlavI

0.0

0.1

0.2

0.3

0.4

0.5

400 500 600 700 800

Re

fle

cta

nce

Wavelength (nm)

Stressed

Healthy


Index EquationStructural indices

**Normalized difference vegetation index (NDVI)

NDVI = (R800 − R670)/(R800 + R670)

**Renormalized difference vegetation index (RDVI)

RDVI = (R800 − R670)/(R800 + R670)°.5

**Optimized soil-adjusted vegetation index (OSAVI)

OSAVI = (1 + 0.16) × (R800 − R670)/(R800 + R670 + 0.16)

Chlorophyll indicesRed edge reflectance index R750/R710

Double peak canopy nitrogen index (DCNI)

DCNI = (R720 − R700)/(R700-R670)/(R720 −R760+0.16)

**Transformed Chlorophyll absorption in reflectance index

(TCARI)

TCARI = 3 [(R700 − R670) − 0.2 (R700 − R550)/(R700/R670)]

**Combined TCARI/OSAVI TCARI/OSAVIXanthophyll indices

Photochemical reflectance index (PRI)

PRI = (R570 − R539)/(R570 + R539)

Normalized photochemical reflectance Index (PRI norm)

PRI norm = (R515 − R531 )/(R515 + R531)

Blue/green/red ratio índicesBGI1 BGI1 = R400/R550

BGI2 BGI2 = R450/R550

Fluorescence retrieval

Fluorescence (SIF760)FLD3 method using 2 reference bands (750;

762; 780)


III. Fertiliser rate vs. N uptake


From: Gabriel et al. 2017. Biosystems Engineering 160, 124-133

http://www.sciencedirect.com/science/article/pii/S1537511017300247

ESTRUCTURAL

PIGMENT

COMBINED

III. Remote sensor predicting N content


From: Gabriel et al. 2017. BiosystemsEngineering 160, 124-133


ESTRUCTURAL PIGMENT

III. Scale resolution effect


From: Gabriel et al. 2017. Biosystems Engineering 160, 124-133


• Proximal and airborne sensors provided useful information for the assessment of maize N nutritional status.

• Higher accuracy was obtained with indexes combining chlorophyll estimation with canopy structure (i.e. TCARI/OSAVI for airborne sensors) or with polyphenol indexes (NBI for proximal sensors, avoiding index saturation).

• The spatial resolution (SR) of the acquired image had an effect on the indexes performance: Structural indexes (NDVI, RDVI or OSAVI) presented low dependency of image SR, whereas pigment indexes (as TCARI) were highly influenced by SR because of the background and shadow effect.

• Further research is needed to identify robust indexes across species and stress levels related to plant N concentration for better monitoring crop N nutritional status.

IV. CONCLUSIONS


Thank you for your [email protected]


monitoring maize n status with airborne and ground level

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